Myoelectric Prosthesis Components for the Upper Limb
Durable Medical Equipment
Original Policy Date
Last Review Status/Date
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Our medical policies are designed for informational purposes only and are not an authorization, or an explanation of benefits, or a contract. Receipt of benefits is subject to satisfaction of all terms and conditions of the coverage. Medical technology is constantly changing, and we reserve the right to review and update our policies periodically.
Myoelectric prostheses are powered by electric motors with an external power source. The joint movement of an upper limb prosthesis (e.g., hand, wrist, and/or elbow) is driven by microchip-processed electrical activity in the muscles of the remaining limb stump.
Upper limb prostheses are used for amputations at any level from the hand to the shoulder. The need for a prosthesis can occur for a number of reasons, including trauma, surgery, or congenital anomalies. The primary goals of the upper limb prostheses are to restore natural appearance and function. Achieving these goals also requires sufficient comfort and ease of use for continued acceptance by the wearer. The difficulty of achieving these diverse goals with an upper limb prosthesis increases with the level of amputation (digits, hand, wrist, elbow, and shoulder), and thus the complexity of joint movement, increases.
Upper limb prostheses are classified into three categories depending on the means of generating movement at the joints: passive, body-powered, and electrically powered movement. All three types of prostheses have been in use for more than 30 years; each possesses unique advantages and disadvantages.
- The passive prosthesis is the lightest of the three types and is described as the most comfortable. Since the passive prosthesis must be repositioned manually, typically by moving it with the opposite arm, it cannot restore function.
- The body-powered prosthesis uses a body harness and cable system to provide functional manipulation of the elbow and hand. Voluntary movement of the shoulder and/or limb stump extends the cable and transmits the force to the terminal device. Prosthetic hand attachments, which may be claw-like devices that allow good grip strength and visual control of objects or latex-gloved devices that provide a more natural appearance at the expense of control, can be opened and closed by the cable system. Patient complaints with body-powered prostheses include harness discomfort, particularly the wear temperature, wire failure, and the unattractive appearance.
- Myoelectric prostheses use muscle activity from the remaining limb for the control of joint movement. Electromyographic (EMG) signals from the limb stump are detected by surface electrodes, amplified, and then processed by a controller to drive battery-powered motors that move the hand, wrist, or elbow. Although upper arm movement may be slow and limited to one joint at a time, myoelectric control of movement may be considered the most physiologically natural. Patient dissatisfaction with myoelectric prostheses includes the increased cost, maintenance (particularly for the glove), and weight.
- Myoelectric hand attachments are similar in form to those offered with the body-powered prosthesis but are battery-powered. An example of recently available technology is the SensorHand™ by Advanced Arm Dynamics, which is described as having an AutoGrasp feature, an opening/closing speed of up to 300 mm/second, and advanced EMG signal processing. The i-LIMB™ hand (Touch Bionics), sometimes referred to as the bionic hand, is the first commercially available myoelectric hand prosthesis with individually powered digits. ProDigits™, also from Touch Bionics, are prosthetic digits for one or more fingers in patients with amputation at a transmetacarpal level or higher. These may be covered by LIVINGSKIN™, a high-definition silicone prosthesis created to resemble a patient’s natural skin.
- A hybrid system, a combination of body-powered and myoelectric components, may be used for high-level amputations (at or above the elbow). Hybrid systems allow control of two joints at once (i.e., one body-powered and one myoelectric) and are generally lighter and less expensive than a prosthesis composed entirely of myoelectric components.
Technology in this area is rapidly changing, driven by advances in biomedical engineering and by the U.S. Department of Defense Advanced Research Projects Agency (DARPA), which is funding a public and private collaborative effort on prosthetic research and development. Areas of development include the use of skin-like silicone elastomer gloves, “artificial muscles,” and sensory feedback. Smaller motors, microcontrollers, implantable myoelectric sensors, and re-innervation of remaining muscle fibers are being developed to allow fine movement control. Lighter batteries and newer materials are being incorporated into myoelectric prostheses to improve comfort.
Manufacturers must register prostheses with the restorative devices branch of the U.S. Food and Drug Administration (FDA) and keep a record of any complaints, but do not have to undergo a full FDA review.
Available myoelectric devices include ProDigits™ and i-LIMB™ (Touch Bionics), the Otto Bock myoelectric prosthesis (Otto Bock), the LTI Boston Digital Arm™ System (Liberating Technologies Inc.), and the Utah Arm Systems (Motion Control).
Myoelectric upper limb prosthetic components may be considered medically necessary when the following conditions are met:
- The patient has an amputation or missing limb at the wrist or above (forearm, elbow, etc.); AND
- Standard body-powered prosthetic devices cannot be used or are insufficient to meet the functional needs of the individual in performing activities of daily living; AND
- The remaining musculature of the arm(s) contains the minimum microvolt threshold to allow operation of a myoelectric prosthetic device; AND
- The patient has demonstrated sufficient neurological and cognitive function to operate the prosthesis effectively; AND
- The patient is free of comorbidities that could interfere with function of the prosthesis (neuromuscular disease, etc.); AND
- Functional evaluation indicates that with training, use of a myoelectric prosthesis is likely to meet the functional needs of the individual (e.g., gripping, releasing, holding, and coordinating movement of the prosthesis) when performing activities of daily living. This evaluation should consider the patient’s needs for control, durability (maintenance), function (speed, work capability), and usability.
A prosthesis with individually powered digits, including but not limited to a partial hand prosthesis, is considered investigational.
Myoelectric upper limb prosthetic components are considered notmedically necessary under all other conditions.
Amputees should be evaluated by an independent qualified professional to determine the most appropriate prosthetic components and control mechanism (e.g., body-powered, myoelectric, or combination of body-powered and myoelectric). A trial period may be indicated to evaluate the tolerability and efficacy of the prosthesis in a real life setting.
BlueCard/National Account Issues
In this policy, procedures are considered reconstructive when intended to address a significant variation from normal related to accidental injury, disease, trauma, treatment of a disease or congenital defect, irrespective of whether a functional impairment is present. This reconstructive benefit may be applied in cases in which the myoelectric prosthesis is requested based on appearance. Not all benefit contracts include benefits for reconstructive services as defined by this policy. Benefit language supersedes this document.
State or federal mandates (e.g., FEP) may dictate that all FDA-approved devices, drugs, or biologics may not be considered investigational and thus these devices may be assessed only on the basis of their medical necessity.
This policy was created in 2008 and, since then, updated periodically using the MEDLINE database. The most recent literature update was performed through April 29, 2013. The majority of studies identified describe the development of interfaces and signal processing algorithms for myoelectric prosthetic control.
Prospective comparative studies with objective and subjective measures would provide the most informative data on which to compare different prostheses, but little evidence was identified that directly addressed whether myoelectric prostheses improve function and health-related quality of life.
The available indirect evidence is based on two assumptions: 1) use of any prosthesis confers clinical benefit, and 2) self-selected use is an acceptable measure of the perceived benefit (combination of utility, comfort, and appearance) of a particular prosthesis for that individual. Most of the studies identified describe amputees’ self-selected use or rejection rates. The results are usually presented as hours worn at work, hours worn at home, and hours worn in social situations. Amputees’ self-reported reasons for use and abandonment are also frequently reported. It should be considered that upper limb amputee’s needs may depend on the particular situation. For example, increased functional capability may be needed with heavy work or domestic duties, while a more naturally appearing prosthesis with reduced functional capability may be acceptable for an office, school, or other social environment.
One prospective controlled study compared preferences for body-powered and myoelectric hands in children. (1) Juvenile amputees (toddlers to teenagers, n=120) were fitted in a randomized order with one of the 2 types of prostheses; after a 3-month period, the terminal devices were switched, and the children selected one of the prostheses to use. After 2 years, some (n=11) of the original study sites agreed to reevaluate the children, and 78 (74% follow-up from the 11 sites) appeared for interview and examination. At the time of follow-up, 34 (44%) were wearing the myoelectric prosthesis, 26 (34%) were wearing a body-powered prosthesis (13 used hands and 13 used hooks), and 18 (22%) were not using a prosthesis. There was no difference in the children’s ratings of the myoelectric and body-powered devices (3.8 on a 5-point scale). Of the 60 children who wore a prosthesis, 19 were considered to be “passive” users, i.e., they did not use the prosthesis to pick up or hold objects (prehensile function). A multicenter within-subject randomized study, published in 1993, compared function with myoelectric and body-powered hands (identical size, shape, and color) in 67 children with congenital limb deficiency and 9 children with traumatic amputation. (2) Each type of hand was worn for 3 months before functional testing. Some specific tasks were performed slightly faster with the myoelectric hand; others were performed better with the body-powered hand. Overall, no clinically important differences were found in performance. Interpretation of these results is limited by changes in technology since this study was published.
Silcox and colleagues conducted a within-subject comparison of preference for body-powered or myoelectric prostheses in adults. (3) Of 44 patients who had been fitted with a myoelectric prosthesis, 40 (91%) also owned a body-powered prosthesis and 9 (20%) owned a passive prosthesis. Twenty-two (50%) patients had rejected the myoelectric prosthesis, 13 (32%) had rejected the body-powered prosthesis, and 5 (55%) had rejected the passive prosthesis. Use of a body-powered prosthesis was unaffected by the type of work; good to excellent use was reported in 35% of patients with heavy work demands and in 39% of patients with light work demands. In contrast, the proportion of patients using a myoelectric prosthesis was higher in the group with light work demands (44%) in comparison with those with heavy work demands (26%). There was also a trend toward higher use of the myoelectric prosthesis (n=16) in comparison with a body-powered prosthesis (n=10) in social situations. Appearance was cited more frequently (19 patients) as a reason for using a myoelectric prosthesis than any other factor. Weight (16 patients) and speed (10 patients) were more frequently cited than any other factor as reasons for non-use of the myoelectric prosthesis.
McFarland et al. conducted a cross-sectional survey of upper limb loss in veterans and service members from Vietnam (n=47) and Iraq (n=50) who were recruited through a national survey of veterans and service members who experienced combat-related major limb loss. (4) In the first year of limb loss, the Vietnam group received a mean of 1.2 devices (usually body-powered), while the Iraq group received a mean of 3.0 devices (typically 1 myoelectric/hybrid, 1 body-powered, and 1 cosmetic). At the time of the survey, upper-limb prosthetic devices were used by 70% of the Vietnam group and 76% of the Iraq group. Body-powered devices were favored by the Vietnam group (78%), while a combination of myoelectric/hybrid (46%) and body-powered (38%) devices were favored by the Iraq group. Replacement of myoelectric/hybrid devices was 3 years or longer in the Vietnam group while 89% of the Iraq group replaced myoelectric/hybrid devices in under 2 years. All types of upper limb prostheses were abandoned in 30% of the Vietnam group and 22% of the Iraq group; the most common reasons for rejection included short residual limbs, pain, poor comfort (e.g., weight of the device), and lack of functionality.
A cross-sectional study from 10 Shriners Hospitals assessed the benefit of a prosthesis (type not described) on function and health-related quality of life in 489 children 2–20 years of age with a congenital below-the-elbow deficiency (specific type of hand malformation). (5) Outcomes consisted of parent- and child-reported quality of life and musculoskeletal health questionnaires and subjective and objective functional testing of children with and without a prosthesis. Age-stratified results were compared for 321 children who wore a prosthesis and 168 who did not, along with normative values for each age group. The study found no clinically relevant benefit for prosthesis wearers compared with non-wearers, or for when the wearers were using their prosthesis. Non-wearers performed better than wearers on a number of tasks. For example, in the 13- to 20-year-old group, non-wearers scored higher than wearers for zipping a jacket, putting on gloves, peeling back the plastic cover of a snack pack, raking leaves, and throwing a basketball. Although prostheses have been assumed to improve function, no benefit was identified for young or adolescent children with this type of congenital hand malformation.
A 2007 systematic review of 40 articles published over the previous 25 years assessed upper limb prosthesis acceptance and abandonment. (6) For pediatric patients the mean rejection rate was 38% for passive prostheses (1 study), 45% for body-powered prostheses (3 studies), and 32% for myoelectric prostheses (12 studies). For adults, there was considerable variation between studies, with mean rejection rates of 39% for passive (6 studies), 26% for body-powered (8 studies), and 23% for myoelectric (10 studies) prostheses. The study authors found no evidence that the acceptability of passive prostheses had declined over the period from 1983 to 2004, “despite the advent of myoelectric devices with functional as well as cosmetic appeal.” Body-powered prostheses were also found to have remained a popular choice, with the type of hand-attachment being the major factor in acceptance. Body-powered hooks were considered acceptable by many users, but body-powered hands were frequently rejected (80–87% rejection rates) due to slowness in movement, awkward use, maintenance issues, excessive weight, insufficient grip strength, and the energy needed to operate. Rejection rates of myoelectric prostheses tended to increase with longer follow-up. There was no evidence of a change in rejection rates over the 25 years of study, but the results are limited by sampling bias from isolated populations and the generally poor quality of the studies included.
Biddiss and Chau published results from an online or mailed survey of 242 upper limb amputees from the United States, Canada, and Europe in 2007. (7) Of the survey respondents, 14% had never worn a prosthesis and 28% had rejected regular prosthetic use; 64% were either full-time or consistent part-time wearers. Factors in device use and abandonment were the level of limb absence, gender, and perceived need (e.g., working, vs. unemployed). Prosthesis rejectors were found to discontinue use due to a lack of functional need, discomfort (excessive weight and heat), and impediment to sensory feedback. Dissatisfaction with available prosthesis technology was a major factor in abandoning prosthesis use. No differences between users and non-users were found for experience with a particular type of prosthesis (passive, body-powered, or myoelectric) or terminal device (hand or hook).
In another online survey, the majority of the 43 responding adults used a myoelectric prosthetic arm and/or hand for 8 or more hours at work/school (approximately 86%) or for recreation (67%), while the majority of the 11 child respondents used their prosthesis for 4 hours or less at school (72%) or for recreation (88%). (8) Satisfaction was greatest (more than 50% of adults and 100% of children) for the appearance of the myoelectric prosthesis and least (more than 75% of adults and 50% of children) for the grasping speed, which was considered too slow. Of 33 respondents with a transradial amputation, 55% considered the weight “a little too heavy” and 24% considered the weight to be “much too high.” The types of activities that the majority of adults (between 50% and 80%) desired to perform with the myoelectric prosthesis were handicrafts, operation of electronic and domestic devices, using cutlery, personal hygiene, dressing and undressing, and to a lesser extent, writing. The majority (80%) of children indicated that they wanted to use their prosthesis for dressing and undressing, personal hygiene, using cutlery, and handicrafts.
A 2009 study evaluated the acceptance of a myoelectric prosthesis in 41 children 2–5 years of age. (9) To be fitted with a myoelectric prosthesis, the children had to communicate well and follow instructions from strangers, have interest in an artificial limb, have bimanual handling (use of both limbs in handling objects), and have a supportive family setting. A 1- to 2-week interdisciplinary training program (in-patient or out-patient) was provided for the child and parents. At a mean 2 years’ follow-up (range 0.7–5.1 years), a questionnaire was distributed to evaluate acceptance and use during daily life (100% return rate). Successful use, defined as a mean daily wearing time of more than 2 hours, was achieved in 76% of the study group. The average daily use was 5.8 hours per day (range 0–14 hours). The level of amputation significantly influenced the daily wearing time, with above elbow amputees wearing the prosthesis for longer periods than children with below elbow amputations. Three of 5 children (60%) with amputations at or below the wrist refused use of any prosthetic device. There were trends (i.e., did not achieve statistical significance in this sample) for increased use in younger children, in those who had in-patient occupational training, and in those children who had a previous passive (vs. body-powered) prosthesis. During the follow-up period, maintenance averaged 1.9 times per year (range of 0–8 repairs); this was correlated with the daily wearing time. The authors discussed that a more important selection criteria than age was the activity and temperament of the child; for example, a myoelectric prosthesis would more likely be used in a calm child interested in quiet bimanual play, whereas a body-powered prosthesis would be more durable for outdoor sports, and in sand or water. Due to the poor durability of the myoelectric hand, this group provides a variety of prosthetic options to use depending on the situation. The impact of multiple prostheses types (e.g., providing both a myoelectric and body-powered prosthesis) on supply costs, including maintenance frequency, are unknown at this time.
An evaluation of a rating scale called the Assessment of Capacity for Myoelectric Control (ACMC) was described by Lindner and colleagues in 2009. (10) For this evaluation of the ACMC, a rater identified 30 types of hand movements in a total of 96 patients (age range 2–57 years) who performed a self-chosen bimanual task, such as preparation of a meal, making the bed, doing crafts, or playing with different toys; each of the 30 types of movements was rated on a 4-point scale (not capable or not performed, sometimes capable, capable on request, and spontaneously capable). The types of hand movements were variations of four main functional categories (gripping, releasing, holding, and coordinating), and the evaluations took approximately 30 minutes. Statistical analysis indicated that the ACMC is a valid assessment for measuring differing ability among users of upper limb prostheses, although the assessment was limited by having the task difficulty determined by the patient (e.g., a person with low ability might have chosen a very easy and familiar task). Lindner et al. recommended that further research with standard tasks is needed and that additional tests of reliability are required to examine the consistency of the ACMC over time.
Although the availability of a myoelectric hand with individual control of digits has been widely reported in lay technology reports, video clips and basic science reports, no peer-reviewed publications were found to evaluate functional outcomes of individual digit control in amputees.
Clinical Input Received through Physician Specialty Societies and Academic Medical Centers
While the various physician specialty societies and academic medical centers may collaborate with and make recommendations during this process, through the provision of appropriate reviewers, input received does not represent an endorsement or position statement by the physician specialty societies or academic medical centers, unless otherwise noted.
In response to requests, input was received from 1 physician specialty society and 4 academic medical centers while this policy was under review in 2008. The American Academy of Physical Medicine and Rehabilitation and all 4 reviewers from academic medical centers supported use of electrically powered upper extremity prosthetic components. Reviewers also supported evaluation of the efficacy and tolerability of the prosthesis in a real-life setting, commenting that outcomes are dependent on the personality and functional demands of the individual patient.
In response to requests, input on partial hand prostheses was received from 1 physician specialty society and 2 academic medical centers while this policy was under review in 2012. Input was mixed. The reviewers agreed that there was a lack of evidence and experience with individual digit control, although some thought that these devices might provide functional gains for selected patients.
The goals of upper limb prostheses relate to restoration of both appearance and function while maintaining sufficient comfort for continued use. The identified literature focuses primarily on patient acceptance and reasons for disuse; detailed data on function and functional status, and direct comparisons of body-powered and newer model myoelectric prostheses are limited/lacking. The limited evidence available suggests that in comparison with body-powered prostheses, myoelectric components may improve range of motion to some extent, have similar capability for light work but may have reduced performance under heavy working conditions. The literature also indicates that the percentage of amputees who accept use of a myoelectric prosthesis is approximately the same as those who prefer to use a body-powered prosthesis and that self-selected use depends at least in part on the individual’s activities of daily living. Appearance is most frequently cited as an advantage of myoelectric prostheses, and for patients who desire a restorative appearance, the myoelectric prosthesis can provide greater function than a passive prosthesis, with equivalent function to a body-powered prosthesis for light work. Nonuse of any prosthesis is associated with lack of functional need, discomfort (excessive weight and heat), and impediment to sensory feedback. Because of the differing advantages and disadvantages of the currently available prostheses, myoelectric components for individuals with an amputation at the wrist or above may be considered when passive or body-powered prostheses cannot be used or are insufficient to meet the functional needs of the patient in activities of daily living. Evidence is insufficient to evaluate full or partial hand prostheses with individually powered digits; these are considered investigational.
Medicare National Coverage
There is no national coverage determination.
- Kruger LM, Fishman S. Myoelectric and body-powered prostheses. J Pediatr Orthop 1993; 13(1):68-75.
- Edelstein JE, Berger N. Performance comparison among children fitted with myoelectric and body-powered hands. Arch Phys Med Rehabil 1993; 74(4):376-80.
- Silcox DH, 3rd, Rooks MD, Vogel RR et al. Myoelectric prostheses. A long-term follow-up and a study of the use of alternate prostheses. J Bone Joint Surg Am 1993; 75(12):1781-9.
- McFarland LV, Hubbard Winkler SL, Heinemann AW et al. Unilateral upper-limb loss: satisfaction and prosthetic-device use in veterans and servicemembers from Vietnam and OIF/OEF conflicts. J Rehabil Res Dev 2010; 47(4):299-316.
- James MA, Bagley AM, Brasington K et al. Impact of prostheses on function and quality of life for children with unilateral congenital below-the-elbow deficiency. J Bone Joint Surg Am 2006; 88(11):2356-65.
- Biddiss E, Chau T. Upper-limb prosthetics: critical factors in device abandonment. Am J Phys Med Rehabil 2007; 86(12):977-87.
- Biddiss EA, Chau TT. Upper limb prosthesis use and abandonment: a survey of the last 25 years. Prosthet Orthot Int 2007; 31(3):236-57.
- Pylatiuk C, Schulz S, Doderlein L. Results of an Internet survey of myoelectric prosthetic hand users. Prosthet Orthot Int 2007; 31(4):362-70.
- Egermann M, Kasten P, Thomsen M. Myoelectric hand prostheses in very young children. Int Orthop 2009; 33(4):1101-5.
- Lindner HY, Linacre JM, Norling Hermansson LM. Assessment of capacity for myoelectric control: evaluation of construct and rating scale. J Rehabil Med 2009; 41(6):467-74.
|V49.64-V49.67||Upper limb amputation status code range|
Fitting and adjustment of prosthetic device and implant; artificial arm (complete) (partial)
|HCPCS||L6025||Transcarpal/metacarpal or partial hand disarticulation prosthesis, external power, self-suspended, inner socket with removable forearm section, electrodes and cables, two batteries, charger, myoelectric control of terminal device|
|L6880||Electric hand, switch or myoelectric controlled, independently articulating digits, any grasp pattern or combination of grasp patterns, includes motor(s)|
|L6925||Wrist disarticulation, external power, self-suspended inner socket, removable forearm shell, Otto Bock or equal electrodes, cables, two batteries and one charger, myoelectronic control of terminal device|
|L6935||Below elbow, external power, self-suspended inner socket, removable forearm shell, Otto Bock or equal electrodes, cables, two batteries and one charger, myoelectronic control of terminal device|
|L6945||Elbow disarticulation, external power, molded inner socket, removable humeral shell, outside locking hinges, forearm, Otto Bock or equal electrodes, cables, two batteries and one charger, myoelectronic control of terminal device|
|L6955||Above elbow, external power, molded inner socket, removable humeral shell, internal locking elbow, forearm, Otto Bock or equal electrodes, cables, two batteries and one charger, myoelectronic control of terminal device|
|L6965||Shoulder disarticulation, external power, molded inner socket, removable shoulder shell, shoulder bulkhead, humeral section, mechanical elbow, forearm, Otto Bock or equal electrodes, cables, two batteries and one charger, myoelectronic control of terminal device|
|L6975||Interscapular-thoracic, external power, molded inner socket, removable shoulder shell, shoulder bulkhead, humeral section, mechanical elbow, forearm, Otto Bock or equal electrodes, cables, two batteries and one charger, myoelectronic control of terminal device|
|L7007||Electric hand, switch or myoelectric controlled, adult|
|L7008||Electric hand, switch or myoelectric controlled, pediatric|
|L7009||Electric hook, switch or myoelectric controlled, adult|
Electric hook, switch or myoelectric controlled, pediatric
|L7190||Electronic elbow, adolescent, Variety Village or equal, myoelectronically controlled|
|L7191||Electronic elbow, child, Variety Village or equal, myoelectronically controlled|
|ICD-10-CM (effective 10/1/14)||Z44.001-Z44.009||Encounter for fitting and adjustment of unspecified artificial arm (code range)|
|Z44.011- Z44.019||Encounter for fitting and adjustment of complete artificial arm (code range)|
|Z44.021-Z44.029||Encounter for fitting and adjustment of partial artificial arm|
|ICD-10-PCS (effective 10/1/14)||Not applicable. ICD-10-PCS codes are only used for inpatient services. There are no ICD procedure codes for devices.|
Upper limb prosthesis
|12/11/08||New Policy||Policy created with literature search; may be medically necessary under specified conditions|
|01/14/10||Replace policy||Policy updated with literature review through November 2009; references 8 and 9 added; specific criteria added|
|03/11/10||Replace policy||Policy updated for prosthesis with individually, controlled digits; policy statements unchanged|
|3/10/11||Replace policy||Policy updated with literature review through January 2011; policy statement unchanged|
|03/08/12||Policy replaced||Policy updated with literature review through December 2011; reference 4 added; policy statement unchanged|
|06/14/12||Policy replaced||Policy updated with literature review through April 2012; clinical input reviewed; individual digit control added to policy; considered investigational|
|6/13/13||Policy replaced||Policy updated with literature review through April 29, 2013; no references added; title changed to “Myoelectric Prosthetic Components for the Upper Limb”; policy statements unchanged|